I have found conflicting charge balances between GWB and PHREEQCI using the same dataset (attached). Results as follows:
Method 1: Manual calculation using major ions only = -30.1%
Method 2: PHREEQCI using llnl.dat = -35%
Method 3: SpecE8 using thermo.com.V8.r6+.dat = -70.18%
Method 4: SpecE8 using thermo.dat = -69.78%
I expect charge balance to be around 30-35%, not 70%!
I have read the thread dated 10/05/2011 entitled, "Charge balance/speciation" where it was commented that discrepancies in charge balances may be attributable to different calculation methods between codes. This does not appear to be the case here as all methods listed above appear to use the following convention:
Charge balance = 100*[(Sum cations–Sum anions)/(Sum cations + Sum anions)]
The issue within SpecE8 doesn't appear to be related to the database used, or to differences in reported calculation methodologies between codes. Have I loaded the input data incorrectly into GWB? I would greatly appreciate your assistance. Thank you.
TD5_40-60_L1-04.sp8